Chosen Solution
Replaced retina screen and now my computer is slow. Followed the directions to a T and so slow. No issues before the screen was put on. I already cleaned it with Mac cleanup and made sure it is updated.
Lots of things can cause a slow down. First start up in Safe Mode by holding down the Shift key on start up and see if the problem persists. Next look to see if your machine is seeing all of your RAM by going to “about this Mac” under the Apple icon. Now do a force quit by holding down the Command and Escape keys and see what you have running in the background. Let us know your results on these things.
